Usually an indicator of Skype running in passive mode, is displayed in the notification area on the taskbar. Click the right mouse button and select in the drop down menu the Quit command ("Exit"). Of necessity, confirm the action in the query window. Application will be closed. If you click the Close ("Close") from the Skype menu in the active window of the program, it will simply be phased out, do not confuse these two actions.
You can also quit a program through task Manager. Press Ctrl, Alt and Del, or right-click the mouse on the taskbar and select the context menu item "task Manager". In the window that opens on the Applications tab, highlight the left click Skype and click "end task". Or, open the tab "Processes", highlight the line Skype.exe and click on "End process".
If Skype starts automatically at each boot of the operating system, and you don't like, set the right settings. Check the startup folder: click start, expand all programs, locate the specified folder, delete from the submenu to Skype.
Another option: open the "My computer", the disk system, select the Documents and Settings folder and in the subfolder "Administrator", locate the start menu programs folder "startup". Then delete the shortcut to the startup file for Skype.
To cancel the automatic start you can configure the program. Open the application window, the Tools menu ("Tools"), select Options ("Options"). In the General settings ("General settings") remove the marker from the field Start Skype when I start Windows ("Start Skype when Windows"). Save the new settings with Save button ("Save").